1. Field of the Invention
The present invention relates to a guide wire for use in medical treatments. More particularly, it relates to a guide wire that is used to make an approach through the duodenal papilla to the pancreatic obiliary duct, by using an endoscope inserted through the mouth.
2. Description of the Related Art
Various types of guide wires are generally known. Some have desired flexibility, each formed by coiling a wire of metal such as stainless steel. Others have a tapered distal part, each made of a single wire of super elastic metal such as nickel-titanium alloy.
Such a guide wire is used to guide an instrument, such as catheter, into a narrow tract or lumen, or to replace the catheter with another. The guide wire may have marking that is fit to the specific use of the guide wire.
U.S. Pat. No. 5,084,022, for example, discloses a guide wire that has marks provided at regular intervals. The mark intervals serve to measure the length of an object.
Jpn. UM Appln. KOKAI Publication No. 4-108556 and Jpn. Pat. Appln. KOKAI Publication No. 2001-46508 disclose guide wires having marking that may be used to confirm the depth to which an instrument is inserted into, for example, the papilla.
U.S. Pat. No. 5,379,779 discloses a guide wire having marking that may be used to determine whether the guide wire moves or not while the catheter is being replaced by another.
Jpn. Pat. Appln. KOKAI Publication No. 11-89940 and Jpn. Pat. Appln. KOKAI Publication No. 11-137693 discloses guide wires having an angled part at the distal end. These guide wires have marking that enables the user to determine visually the position or orientation of the angled part.
The marking on any conventional guide wire described above helps the user to determine mainly the posture, position or motion of the guide wire.
However, the conventional guide wires having marking are disadvantages in the following respects.
A first disadvantage will be explained with reference to FIG. 3A.
To replace a catheter inserted in the papilla with another catheter, only the catheter (not shown) is usually pulled back, pulling its distal end into the endoscope 102, while the guide wire remains inserted in the papilla. Then, the hebel 103 at the distal end of the endoscope is raised to the uppermost position, bending the guide wire 1 and fastening the same to the endoscope.
When the guide wire 1 is bent at the distal part, the force fastening the wire 1 to the endoscope cannot be sufficient because the distal part is soft. If the guide wire 1 is bent at the distal part that is soft, the fastening force is so small that the guide wire 1 may move in the direction of the arrow while the catheter is being replaced with another. If the guide wire 1 is so moves, it may slip from the papilla or a narrow tract.
A second disadvantage will be explained, with reference to FIG. 3B.
Assume that a stent (not shown) or a catheter 104 mounted on a guide wire 1 is being inserted into the capilla or the like. If the distal part of the guide wire 1 has been inserted a little into the capilla, the stent or catheter is more rigid than the distal part of the guide wire 1. Hence, the guide wire is straightened along the stent or catheter and is no longer bent.
As the stent or catheter 104 is moved forward in this condition, the distal part of the guide wire 1 may slip from the papilla. Then, the catheter can no longer be replaced in some cases. The distal part of the guide wire may be coated with lubricant for smooth insertion. In this case, the guide wire will be more likely to slip from the papilla if an error is made, however small the error is, in manipulating the stent or catheter while only the distal end of the guide wire remains inserted in the papilla.
The position that the distal end of the conventional guide wire takes with respect to the endoscope cannot be confirmed while the guide wire is being manipulated, even though the guide wire has marking. It is therefore demanded that the guide wire be improved in operability.